1. Field of the Invention
The present invention relates to a torque converter comprising a torque input member, a torque output member, a pump impeller, a turbine runner and a stator, wherein the torque converter is designed to circulate fluid between respective ones of the pump impeller, the turbine runner and the stator so as to transmit torque from the torque input member to the torque output member through the fluid, and more particularly to a distinctive technique of reducing an axial dimension of such a torque converter.
2. Background Art
Heretofore, there has been known a torque converter comprising a torque input member, a torque output member, a pump impeller interlocked with the torque input member, a turbine runner disposed in opposed relation to the pump impeller and interlocked with the torque output member, and a stator having a bladed portion (hereinafter referred to as “stator blade portion”) disposed between respective inner peripheral portions of the pump impeller and the turbine runner, wherein the torque converter is designed to circulate fluid between respective ones of the pump impeller, the turbine runner and the stator blade portion (i.e., circulate fluid along a torus flow circuit defined by the pump impeller, the turbine runner and the stator blade portion) so as to transmit torque from the torque input member to the torque output member through the fluid.
For example, in a torque converter for use in automobiles, the torque input member and the torque output member are connected to an engine and a speed change mechanism of an automatic transmission, respectively. In this case, a power train between the engine and the automatic transmission is serially arranged and is thereby apt to have a relatively long overall length. Recent years, there has been a growing need for downsizing an engine compartment serving as a mounting space of a power train. In connection with this need, it has been increasingly required to accelerate reduction in overall length of a power train and therefore reduction in axial dimension of a torque converter.
For example, as a technique of reducing an axial dimension of a torque converter, JP 2006-118654A discloses a hydraulic torque converter. This torque converter includes a lockup clutch mechanism for mechanically connecting a torque input member (front cover) directly to a torque output member (turbine hub), and a damper device for absorbing fluctuations in torque to be transmitted from the torque input member to the torque output member during engagement of the lockup clutch mechanism. The torque converter is intended to improve a layout of the turbine hub and the damper device so as to reduce an axial dimension of the torque converter.
In the above torque converter, a one-way clutch is provided on the side of an inner peripheral portion of a stator, and two thrust bearings are disposed on respective axially-opposite sides of the inner peripheral portion of the stator at respective positions located axially outwardly relative to the one-way clutch, to receive a thrust force acting on the stator.
In view of meeting the increasing need for reducing an axial dimension of a torque converter, it is strongly desired to develop more effective downsizing techniques.